In the broadest sense, “beer” is any alcoholic beverage made by the fermentation of grain, just as wine is any alcoholic beverage made by the fermentation of fruit. In the vast majority of the world’s beers, the grain base is barley.
The brewing process commonly begins with malted barley, or “malt”—barley that has been germinated then roasted. The brewer mills the malt, cracking the grains between rollers to expose more surface area. Then, just as coffee grounds are steeped in hot water to extract their flavors, the malt is heated with water in a large kettle called a “mash tun.” At the end of mashing, the starches in the malt have been broken down into simple sugars, resulting in a sweet liquid known as “wort.”
The brewer rinses the malt (“sparging”) and strains it to get the last of the sugars into solution. The used malt is now “spent grain,” useless for beer, but still good for baking, or for animal feed.
The wort is piped into the next large tank in the brewery, the brew kettle. Here, hops (green, cone-like flowers) are added and boiled with the liquid, providing bitterness and aroma.
After boiling, the wort is rapidly cooled until it is at the right temperature to add yeast, the single-celled organisms that do the work of fermentation. The yeast is pitched in to the sweet wort, where it consumes the sugar, releasing alcohol and carbon dioxide in the process.
After a while, the food runs low, and the increasingly alcoholic atmosphere becomes unfriendly: the yeast slow down, or even die. Fermentation is complete. The young beer is transferred to conditioning tanks to age, a process that can go from a few days to several weeks (or, occasionally, years) depending on the style. When the brewer decides the beer ready, the public gets to enjoy this work of art.
Water in Beer
Brewing has traditionally been an activity based on local materials. Agricultural ingredients—barley and hops—might be transported to the brewery from the countryside, and, with improvements in trade, from even further afield. But the heaviest and most ubiquitous ingredient, water, has always been—and still is—local.
That means that the chemical composition of a brewery’s water, which depends on local geology, has had a profound influence on the character of local beer. In particular, the hardness or softness of the water (meaning water with a higher or lower mineral content, mainly calcium and magnesium, and also bicarbonate) is behind the special qualities of beer styles we associate with particular locations.
For example, regions with high levels of bicarbonate in their water, such as London or Dublin, have become known for their darker beers. This is because bicarbonate affects the pH (acid-alkaline) of the water. Yeast don’t perform well faced with too high a pH (higher alkalinity). Brewers gradually learned that if used roasted barley, which makes a dark beer, the result was better. Though they didn’t realize it, the addition of roasted barley had the effect of lowering the pH.
By contrast, the Czech town of Pilsen has very soft water. Its purity contributed to the startling clean, fresh flavors of Pilsner Urquell, the very first pilsner beer.
Compare that to Burton-on-Trent in England, birthplace of pale ale. The water of the River Trent is very hard, and especially rich in calcium sulphate (gypsum). This allowed the town’s famous pale ales to feature the bitterness of hops so elegantly, and added a whiff of characteristic sulphur. In fact, the water of Burton is so famous that brewers the world around who want to brew pale ales may “Burtonize” their water, adding minerals to mimic the original.
Today, brewing chemists can alter the composition of any water supply to suit the style of beer being brewed. Despite the attention given to beer’s other three ingredients, the old ad got it right with the tag line “It’s the water.”
Malt in Beer
Although wheat, rye, oats, millet, sorghum, rice and corn have all been used for brewing, barley is the preferred grain for beer. But the starch in a grain of barley isn’t ready to be fermented into alcohol, so the barley is generally converted into malted barley, or “malt.” The process of malting involves soaking the barley, allowing it to germinate, and then stopping germination with heat.
The amount of heating that barley malt receives has profound effects on the sort of beer that will be brewed. All the color in beer comes from the malted barley. A lightly-roasted malt will produce a very pale beer. Deeply roasted malts produce dark or black beers.
So, take lightly roasted malt and make a beer from it. Use an ale yeast, and the result will be a pale ale, the classic English pub beer, or a bitter or golden ale. Use a lager yeast, and the result will be a style such as pilsner.
Use a malt with more of a golden roast, and the ale variety will be an amber ale or a Scottish ale; if a lager, perhaps it will be a Märzen, a festbier or an Oktoberfest beer—all beer styles with a slighter sweeter character.
Give the malt a little more heat, and the beers become darker, more the color of root beer. Brown ales—Newcastle Brown is a classic—are the ale variety. In the lagers, the cleaner tasting German dunkels—dark lagers—are the counterparts.
The popular wisdom is that these dark beers are stronger than light beers. On the contrary, the roasting may have the effect of “locking up” some of the starches in the beer so they cannot be fermented. There is less food for the yeast to turn to alcohol; the beers may be lower in alcohol, and the unfermented material stays in the beer, giving it a thicker texture in your mouth. The beers can feel rich, but actually may be less intoxicating than a mass-marketed lager.
More roasting. The next darker beers are porters and stouts (which are ales) and the rather rare schwarzbiers (black lagers). In keeping with the differences between the two families, porters will have a lot more spin-off flavors, such as fruity notes, than the schwarzbiers, which will be malty (sweet) but still very clean. Both styles acquire coffee or chocolatey notes from their dark malts. With stouts, the blackest of the ales, the addition of roasted barley can give the beer a burnt-toast edge.
Thanks to malt, lagers and ales both come in a full range of colors, strengths, and characters.
Hops in Beer
There are four basic ingredients to beer, but only three are essential: malted barley, yeast and water. However, beer made with only these three will be sickly-sweet and dull. Throughout brewing history, brewers have added something extra—usually a plant part of some sort—to give their beer balance and depth.
They’ve added heather flowers, spruce tips, borage or bog myrtle. In the Middle Ages, brewers flavored their beer with a mixture called “gruit” that combined herbs and spices in recipes that varied from place to place.
But by the 15th century, one vigorous weed crowded out all the others as the fourth ingredient in beer: hops. Hop plants are climbing vines (more accurately, bines: vines without tendrils). The plant part used in brewing beer is the hop flower, a delicate, pale green, papery cone full of perishable resins. They give a beer bitterness when used early in the brewing process, and aroma when added at the end. As a bonus, hops are a preservative, and extend the life of beer.
In the hands of American microbrewers, hops have moved from their position as the supporting actor in the beer ensemble to the starring role.
West Coast microbrewers led the way in creating beers where the character of hops—bitter, piney, grassy, floral, or grapefruity—took center stage. Beer lovers took pride in seeking out the brews with higher and higher IBUs—international bittering units, the measure of the concentration of hop compounds in beer.
High-hopped beers are not for every taste. But for the hop lovers out there, there is a stunning array of hop varieties—with new ones being developed all the time—that brewers employ singly or in combination.
Now, American brewers have boosted the hopping levels of their IPAs to such an extent that a new beer style has emerged: so-called double or “imperial” India pale ale. These big beers feature even more hop power and alcohol to match.
Yeast in Beer
The most important ingredient in brewing was the last one discovered, because yeast is a single-celled organism that is invisible to the naked eye. Still, brewers have long known that some unseen agent turned a sweet liquid into beer. Long ago, the action of yeast was such a blessing, yet so mysterious, that English brewers called it “Godisgood.”
Modern brewers usually brew with purified strains of yeast that give exactly the result they want. Some yeast strains are fairly neutral, creating alcohol and little more. Others add a whole range of complex side flavors that make beer more interesting.
How does yeast work? When it is added to a sugar-rich solution, it immediately begins to consume the sugars and create more yeast. But from the brewer’s point of view, the important thing is not the growth of more yeast, but the waste products of yeast metabolism: alcohol and carbon dioxide, that gives beer its fizz.
As the food supply runs down and the alcohol levels rise, the environment becomes literally toxic to the yeast, which becomes dormant. The brewer may draw off some of the yeast for the next cycle of brewing.
Ale or Lager?
Different strains of yeast behave differently, so that it’s possible to divide the world of beer according to the yeast. The sixty or more defined beer styles in the world can all be sorted by their yeast into two broad families: the ale family and the lager family.
Beers in the ale family are produced by yeast strains that operate better at warmer temperatures. Ales are ready to drink in days rather than weeks, and the yeasts produce extra flavors in addition to creating alcohol: fruity, spicy, or earthy flavors are not unusual. Ales are the traditional beers of England and of Belgium.
Beers in the lager family are fermented by yeast strains that operate better at cooler temperatures. These beers need to be conditioned or cellared (“lager” is German for a storage place) for several weeks or more to reach peak drinkability. The lager beers are the traditional beers of Germany, the Czech Republic and central Europe.
The action of yeast can generate a range of interesting beer flavors and aromas as varied as apple, pepper or apricot. Some, such as banana or clove, are the typical flavors of particular beer styles; others, such as butterscotch, may be considered defects.
Yeast may be invisible, but without it, there would be no beer.